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From: Thomas Gleixner <tglx@linutronix.de>
To: Ira Weiny <ira.weiny@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Fenghua Yu <fenghua.yu@intel.com>,
	linux-doc@vger.kernel.org, linux-nvdimm@lists.01.org,
	linux-mm@kvack.org, linux-kselftest@vger.kernel.org,
	Dan Williams <dan.j.williams@intel.com>,
	Greg KH <gregkh@linuxfoundation.org>
Subject: Re: [PATCH V3 05/10] x86/entry: Pass irqentry_state_t by reference
Date: Mon, 16 Nov 2020 21:36:24 +0100	[thread overview]
Message-ID: <87lff1xcmv.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201116184916.GA722447@iweiny-DESK2.sc.intel.com>

Ira,

On Mon, Nov 16 2020 at 10:49, Ira Weiny wrote:
> On Sun, Nov 15, 2020 at 07:58:52PM +0100, Thomas Gleixner wrote:
>> > Currently struct irqentry_state_t only contains a single bool value
>> > which makes passing it by value is reasonable.  However, future patches
>> > propose to add information to this struct, for example the PKRS
>> > register/thread state.
>> >
>> > Adding information to irqentry_state_t makes passing by value less
>> > efficient.  Therefore, change the entry/exit calls to pass irq_state by
>> > reference.
>> 
>> The PKRS muck needs to add an u32 to that struct. So how is that a
>> problem?
>
> There are more fields to be added for the kmap/pmem support.  So this will be
> needed eventually.  Even though it is not strictly necessary in the next patch.

if you folks could start to write coherent changelogs with proper
explanations why something is needed and why it's going beyond the
immediate use case in the next patch, then getting stuff sorted would be
way easier.

Sorry my crystalball got lost years ago and I'm just not able to keep up
with the flurry of patch sets which have dependencies in one way or the
other.

>> The resulting struct still fits into 64bit which is by far more
>> efficiently passed by value than by reference. So which problem are you
>> solving here?
>
> I'm getting ahead of myself a bit.  I will be adding more fields for the
> kmap/pmem tracking.
>
> Would you accept just a clean up for the variable names in this patch?  I could
> then add the pass by reference when I add the new fields later.  Or would an
> update to the commit message be ok to land this now?

Can you provide a coherent explanation for the full set of things which
needs to be added here first please?

Thanks,

        tglx

  reply	other threads:[~2020-11-16 20:36 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-06 23:28 [PATCH V3 00/10] PKS: Add Protection Keys Supervisor (PKS) support V3 ira.weiny
2020-11-06 23:28 ` [PATCH V3 01/10] x86/pkeys: Create pkeys_common.h ira.weiny
2020-11-06 23:29 ` [PATCH V3 02/10] x86/fpu: Refactor arch_set_user_pkey_access() for PKS support ira.weiny
2020-11-06 23:29 ` [PATCH V3 03/10] x86/pks: Add PKS defines and Kconfig options ira.weiny
2020-11-06 23:29 ` [PATCH V3 04/10] x86/pks: Preserve the PKRS MSR on context switch ira.weiny
2020-12-17 14:50   ` Thomas Gleixner
2020-12-17 22:43     ` Thomas Gleixner
2020-12-18 13:57       ` Thomas Gleixner
2020-12-18 19:20         ` Dan Williams
2020-12-18 21:06           ` Thomas Gleixner
2020-12-18 21:58             ` Dan Williams
2020-12-18 22:44               ` Thomas Gleixner
2020-12-18 19:42         ` Ira Weiny
2020-12-18 20:10           ` Dave Hansen
2020-12-18 21:30           ` Thomas Gleixner
2020-12-18  4:05     ` Ira Weiny
2020-12-17 20:41   ` [NEEDS-REVIEW] " Dave Hansen
2020-12-18  4:10     ` Ira Weiny
2020-12-18 15:33       ` Dave Hansen
2020-11-06 23:29 ` [PATCH V3 05/10] x86/entry: Pass irqentry_state_t by reference ira.weiny
2020-11-15 18:58   ` Thomas Gleixner
2020-11-16 18:49     ` Ira Weiny
2020-11-16 20:36       ` Thomas Gleixner [this message]
2020-11-24  6:09   ` [PATCH V3.1] entry: " ira.weiny
2020-12-11 22:14     ` Andy Lutomirski
2020-12-16  1:32       ` Ira Weiny
2020-12-16  2:09         ` Andy Lutomirski
2020-12-17  0:38           ` Ira Weiny
2020-12-17 13:07       ` Thomas Gleixner
2020-12-17 13:19         ` Peter Zijlstra
2020-12-17 15:35           ` Andy Lutomirski
2020-12-17 16:58     ` Thomas Gleixner
2020-11-06 23:29 ` [PATCH V3 06/10] x86/entry: Preserve PKRS MSR across exceptions ira.weiny
2020-12-17 15:28   ` Thomas Gleixner
2020-11-06 23:29 ` [PATCH V3 07/10] x86/fault: Report the PKRS state on fault ira.weiny
2020-11-06 23:29 ` [PATCH V3 08/10] x86/pks: Add PKS kernel API ira.weiny
2020-12-23 20:39   ` Randy Dunlap
2020-11-06 23:29 ` [PATCH V3 09/10] x86/pks: Enable Protection Keys Supervisor (PKS) ira.weiny
2020-11-06 23:29 ` [PATCH V3 10/10] x86/pks: Add PKS test code ira.weiny
2020-12-17 20:55   ` Dave Hansen
2020-12-18  4:05     ` Ira Weiny
2020-12-18 16:59       ` Dan Williams
2020-12-07 22:14 ` [PATCH V3 00/10] PKS: Add Protection Keys Supervisor (PKS) support V3 Ira Weiny
2020-12-08 15:55   ` Thomas Gleixner
2020-12-08 17:22     ` Ira Weiny

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